I've recently been looking at the Welsh language statistics for Wales by county (and no, I don't get out much) and they make interesting reading. The highest percentages of those able to speak Welsh in predominanlty English-speaking areas of Wales are in the under-16 age groups. This presumably is due to the fact that Welsh is taught in schools up to this age but language use generally declines afterwards.
I think the key for increasing Welsh language usage and indeed the numbers of Welsh learners is to ensure that Cymraeg is spoken both in the home and in the community. The issue is that many parents of children who are learning Welsh in school have little of the language themselves and so these children tend not to use much Welsh outside the classroom.
If we can somehow 'normalise' the use of Welsh in the home (and not suggesting using Welsh in the home is currently abnormal!) where children have some Welsh skills but their parents do not if would be a huge aid in helping children retain those skills. SaySomething in Welsh is ideal for parents to learn Welsh but if their confidence in the language is low then they can simply start by using a few words or a few sentences - e.g. asking their children in Welsh what they want for dinner, asking about their day, if they want a drink etc. Just everyday common phrase, sentences and questions. Then they could start to substitute English words for Welsh words, such as ystafell fyw for living room, llyfr for book, teledu for television etc. Such small steps can make a big difference! That could then move on to having an hour a day, every day, when only Welsh is spoken (a difficult feat with teenagers who can go for hours communicating using nothing but a grunt), using these small steps to build up everyday normal usage of Welsh at home.
Welsh as a community language though is a different prospect in areas that generally have low numbers of Welsh speakers, but there is not a corner of Wales where people are unable to speak Welsh, even if they don't. It would be great to make the Welsh language more visible in these areas. If businesses, particularly such as cafes, restaurants and pubs, were willing to display what level of Welsh service they provide or even partner with a program such as Say Something in Welsh to help staff increase Welsh language ability it could provide a huge boost to the language and also boost business from both leavesarners and fluent speakers. A bilingual cafe would be great, a place where you could go to practice Welsh in the community, chat about the weather (mae hi'n bwrw glaw) and ask for a coffee in Welsh but still order your lunch in English if you wanted. It would be a place to meet other learners and fluent speakers ( and perhaps for a learner to pick up the nuances of local Welsh dialect to help keep it alive) but also a great place for visitors and tourists to hear the spoken language and even try a phrase or two.